Treated phosphates



w- 7, 1968 s. GOLDWASSER 3,

TREATED PHOSPHATES Filed March 24, 1967 v NEEDLE-LIKE CRYSTALS PLATE-LIKE CRYSTALS (ABOUT ZOOX MAGNIFICATION) (ABOUT 200x MAGNIFICATION) INVENTOR. SEYMORE GOLDWASSER his ATTORNEYS.

United States Patent 3,417,024 TREATED PHOSPHATES Seymore Goldwasser, Teaneck, N.J., assignor to Lever Brothers Company, New York, N.Y., a corporation of Maine Continuation of application Ser. No. 334,734, Dec. 31, 1963. This application Mar. 24, 1967, Ser. No. 625,884 11 Claims. (Cl. 252-135) ABSTRACT OF THE DISCLOSURE This disclosure is concerned with a detergent tablet which has a high strength after compression. This detergent tablet contains a synthetic organic nonionic detergent, a phosphate, 0.48% to 2.6% sodium hydroxide, potassium hydroxide or silicates as a source of Na O or K 0 for forming a solution in water with a concentration based on equivalents of Na O of at least 23.5% as NaOH and 2% to 11% water.

This is a continuation application of Ser. No. 334,734 filed on Dec. 31, 1963, now abandoned.

This invention relates to treated phosphates. More particularly, it is concerned with detergent tablets or briquettes containing the treated phosphates.

A process for preparing detergent tablets and the products therefrom are disclosed in copending Black and Gray application, Ser. No. 122,641, filed July 10, 1961 noW abandoned. A description of the Black and Gray detergent tablets and process is included herein since it relates to the present invention.

BLACK AND GRAY DETERGENT TABLETS The detergent tablets contain two classes of essential components, namely nonionic detergent and phosphate, which are used in certain critical amounts and have a certain critical nature as set forth hereinafter.

The detergent briquettes contain from about 4% to about 13% by weight, and preferably from about to about 12% by weight, of one or more synthetic organic nonionic nonsoap detergents. The nonionic detergents are a well-known class of low sudsing detergents and are produced by the condensation of several moles of a hydrophilic alkylene oxide, such as ethylene oxide or propylene oxide, with a hydrophobic base, such as an alkylated phenol, a fatty alcohol, a fatty amine, a fatty amide, or the hydrophobic base formed by the condensation of propylene oxide with propylene glycol. The alkyl phenolalkylene oxide condensates are generally prepared by condensing one mole of an alkyl phenol having from about 9 to about carbon atoms in the alkyl radical with from about 8 to about moles of an alkylene oxide, such as ethylene oxide or propylene oxide. Specific examples thereof are the condensation product of one mole of dodecyl phenol with an average of 10 moles of ethylene oxide sold commercially under the name Sterox DI, the condensation product of 1 mole of nonyl phenol with an average of 9 moles of ethylene oxide sold commercially under the name .Igepal CO-630, the condensation product of 1 mole of nonyl phenol with an average of 10 moles of ethylene oxide sold commercially under the name Tergitol NPX, and the condensation product of 1 mole of nonyl phenol with an average of 20 moles of ethylene oxide sold commercially under the name Igepal CO-850. Typical of the nonionic detergents which are condensation products of a fatty alcohol with an alkylene oxide is the condensate of 1 mole of tridecyl alcohol with an average of 10 moles of ethylene oxide sold commercially under the name Sterox AJ-100. Condensates of tall oil with alkylene oxides also form nonionic detergents. Typical of these is the condensate of 1 mole of tall oil with an average of 10 moles of ethylene oxide sold commercially under the name Sterox CD.

The polyoxyalkylene alk-anols are also nonionic detergents and are made by the condensation of an alkylene oxide with a hydrophobic base formed by the condensation of propylene oxide with propylene glycol. These nonionic detergents, which are described in US. Patent No. 2,674,619 and are sold under the name Pluronic, have the following empirical formula HO 2 4 a. 3 4 b 2 4 C The hydrophobic base portion of this nonionic detergent, i.e., the (C H O) portion, generally has a molecular weight from 801 to 2100. The amount of ethylene oxide in these compounds is represented by the sum of a plus 0 which is an integer such that the molecule contains from 0 to 90% of ethylene oxide. Thus, in Pluronic L-60 b represents a molecular weight of 1501 to 1800 and a plus 0 is an integer such that the molecule contains 0-10% ethylene oxide. In Pluronic L-61 b represents a molecular weight of 1500-1800 and a plus 0 is an integer such that the molecule contains 10 to 20% ethylene oxide. In Pluronic L-64 b represents a molecular weight of 1501-1800 and a plus 0 is an integer such that the molecule contains 40-50% ethylene oxide. In Pluronic F-38 b represents a molecular weight of 801-1000 and a plus 0 is an integer such that the molecule contains 80-90% ethylene oxide. In Pluronic F-68 12 represents a molecular weight of 1501-1800 and a plus 0 is an integer such that the molecule contains 80-90% ethylene oxide. In Pluronic P- [1 represents a molecular weight of 1801- 2100 and a plus 0 is an integer such that the molecule contains 50-60% ethylene oxide.

Other suitable nonionic detergents are the diethanolamides of long chain fatty acids, such as lauric diethanolamide.

The phosphate component of the detergent briquettes is present therein in an amount from about 20% to about 95% by weight, and preferably in an amount of about 60% by weight. This amount of phosphate substantially prevents bleeding or oiling out or separation from the tablets of any normally liquid or oily nonionic detergent present therein. The lower the level of normally liquid or oily nonionic detergent present, the less phosphate is needed to prevent bleeding.

The phosphate can be tetrapotassium pyrophosphate, or pentasodium or pentapotassium tripolyphosphate. The tripolyphosphate as used can be completely anhydrous or the commercial anhydrous variety containing small amounts of water, either uncombined or in the form of small amounts of tripolyphosphate hexahydrate up to, for example, about 1%.

When sodium tripolyphosphate is used, it may be Type II (wherein the tripolyphosphate content contains at least 95 Form II), or if rapid disintegration as Well as rapid solubility is desired, it must be a mixture of Form I and Form IIin which one form may vary from 10% to 90%, and the other from 90% to 10% respectively, in order for the resulting detergent tablets to have a high rate of disintegration, even in unagitated water, as well as rapid solubility in water. Commercial Type I sodium tripolyphosphate containing about 20% Form I and Form II is suitable. Detergent tablets prepared from completely anhydrous or commercial anhydrous Type II sodium tripolyphosphate have relatively slow disintegration rates but acceptable solubility rates.

Detergent tablets prepared by using a tripolyphosphate which is entirely in the hexahydrate form are unsatisfactory, because such tablets have a relatively poor rate of disintegration and solubilization. If desired, however, a portion of the tetrapotassium pyrophosphate of pentasodium or pentapotassium tripolyphosphates can be substituted by other phosphates. Thus there can be substituted an amount up to about 50% of trisodium orthophosphate,

ing the surface of the tablets is critical, because the use of 0.5% or more by weight of water on the tablet surfaces causes the surface to swell and pull away from the body of the tablets and thereby form a very fragile shell. This shell is very easily cracked and flakes away from the tablet leaving a core of untreated tablet which generally lacks suflicient abrasion resistance. This does not lessen friability but rather increases it. Moreover, the use of 0.5% or more by weight of water in the surface moistening treatment may also cause unsightly protuberances to appear on the surface of the tablets.

When surface moistening is employed, the pellets are aged for a time up to 8 hours or longer after the moistening treatment to harden the surface of the pellets. This aging can be performed at room temperature or higher, although the aging temperature should not be so high as to have a deleterious effect on any of the components in the tablet, such as any perfume which might be present therein.

The formulations set forth above in Table A are representative of those which were used in the above described Black and Gray process to produce detergent tablets.

The detergent tablets of the above Table A were tested for abrasion resistance by rubbing them with a plain woven cotton cloth for three minutes. After this abrasion treatment, the pellets showed no loss in weight and the surface of the pellets remained smooth.

The fracture strength of these tablets was at least 10 pounds and in some instances as high as 40 pounds after 24 hours aging. The fracture strength of these tablets was determined by a test which consisted in standing a tablet on edge on a spring scale and then pressing a lever down on the tablets until they fractured.

These tablets were tested to determine their rate of disintegration and solubilization by placing a tablet in a Washing machine containing water having a temperature of 100 F. and measuring the time elapsed until the tablet had completely disintegrated (broke into small fragments) and dissolved. The detergent tablets of Formulations 1-22 had an extremely rapid disintegration and solubilization rate in this test in view of the fact that they completely disintegrated and dissolved within one minute. The tablets of Formulations 23 and 24 did not disintegrate in this test, although they completely dissolved in 3 minutes.

The amount of bleeding, oiling-out or separation of any normally liquid nonionic detergent component from these detergent tablets was determined by placing the tablets on brown absorbent paper and observing any dampening of the paper. These tablets showed no bleeding when left in contact with the absorbent medium for 48 hours.

CRYSTALLIZATION IN BLACK AND GRAY TABLETS It is believed that a rapid growth of undesirable type of crystals in the phosphate, such .as sodium tripolyphosphate, occurs when there is a nucleatin-g agent, i.e., acid decomposition products of the phosphate, on the surface of the Black and Gray tablet. The decomposition products are considered to be acid orthoand pyro-phosphates. The undesirable crystals, caused by these acid decomposition products, are large enough to penetrate and break up the matrix of the detergent, e.g., a waxy, nonionic detergent. If the detergent is acting as an interim binder, this will decrease its binding effectiveness. Furthermore, the interlacing undesirable crystals may eventually lock the internal structure of the tablet together, and the tablet will disintegrate slowly in Water. Therefore, an undesirable type of crystallization during the agglomerating and compressing steps adversely affects the initial strength of the tablet after compression, and it adversely affects subsequently the solubility of the tablets.

The aforementioned undesirable type of crystals are needle-like crystals. Apparently, the water in the hydrated phosphate in the tablet causes growth in the longitudinal direction only to form the needle-like crystals. Needlelike crystals define a certain type of crystal formation known in the art [Industrial Microscopy, L. C. Lindsley, William Byrd Press, Inc. (1929); Handbook of Chemical Microscopy, E. M. Chamot et =al., vol. I (1928)]. The undesirable needle-like crystals provided by the acid decomposition products of the phosphate are indicated schematically in FIGURE 1. I

The crystals described herein are further defined in accordance with the procedure for determining the crystallization in sodium tripolyphosphate. In this procedure, approximately 0.20 gram of sodium tripolyphosphate are placed on a 3" x 1" x 1 mm. microslide. Five to eight drops of water from a stirring rod are added to the sodium tripolyphosphate granules on the microslide. A 25 sq. mm. glass coverslide is placed immediately on top of the granules and it is tilted to one side in order to form a thin film of liquid and granules. The slide is observed at 3 minute intervals for 12 minutes by using a microscope adjusted to magnifications with polarized light. The crystal formation in the phosphate, per se, is considered to be the same as the crystal formulation in a table containing a detergent, such as a nonionic detergent, and a phosphate, such as sodium tripolyphosphate.

IMPROVED TAB-LETS OF THE INVENTION It has now been discovered that the presence of a critical amount and concentration of caustic, such as sodium hydroxide, in the tablet substantially prevents the formation of undesirable dendritic, needle-like crystals therein. Thus, in accordance with .a first embodiment of the invention, a mixture is formed comprising a detergent, a phosphate, 0.48% to 2.6% caustic and 2% to 11% water in order that there is a concentration of at least 23.5% caustic in water. Generally, the mixture is agglomerated to form granules which are then screened. The mixture, with or without agglomerating and screening, is compressed subsequently into the shape of tablets. By employing the critical amount and concentration of caustic in the tablet, the crystal growth therein takes place in all directions to form plate-like crystals. 'The presence of the plate-like crystals do not have an adverse effect upon the initial strength of the compressed tablets and upon the solubility of the tablets in water.

Plate-like crystals are also known [Industrial Microscopy, supra; Handbook of Chemical Microscopy, supra], and they define a certain type of crystal formation. The crystals is recognized in the art. The desirable plate-like crystals are illustrated schematically in FIGURE 2.

Tablets are one of the four basic forms of detergent compositions. They are formed by compressing granules, and they are characterized by their relatively fast dissolving and disintegrating properties. Therefore, the terminology tablets does not include the three other forms of detergent compositions, i.e., particulate compositions, such as powders, beads, flakes, chips and agglomerates; fluid compositions, such as liquids, and pastes; and bars or cakes formed by casting or extruding and characterized by their relatively slow dissolving and disintegrating properties.

As stated heretofore, it is critical to use between 0.48% and 2.6% of caustic with a concentration of at least 23.5% in water contained in the detergent tablet. If less than 0.48% of caustic is employed or if the concentration is less than 23.5%, it will not prevent sufficiently the formation of the undesirable needle-like crystals and it will not permit or promote sufficiently the formation of the plate-like crystals. 1f more than 2.6%, e.g., 2.8% of caustic is employed, no crystallization will occur and the mixture, e.g., the agglomerated mixture, will be mushy. Therefore, it is necessary to have plate-like crystals in the tablet in order to bind the particles therein in a manner to provide a product having the required initial strength after compression for handling and packaging and having the required solubility in water, i.e., less than 1% minutes with the usual conditions of an operating washing machine.

Caustic is defined in the present invention as an alkali material which is a source of Na O or K and which is capable of forming a solution in water with a concentration, based on equivalents of Na O, of at least 23.5% as NaOH. The following compounds, among others, are within the purview of this definition: sodium hydroxide, potassium hydroxide and silicates, e.g.,

Na O 2.4SiO

Therefore, the 0.48% to 2.6% caustic in the tablet is the weight of equivalent Na O based on the total weight of the tablet.

A phosphate is another essential ingredient in the detergent tablet of the invention. The amount of phosphate is not critical; however, it is generally between about and about 95% by weight, preferably between 40% and 70%, based upon the total weight of the tablet. As defined herein, a phosphate is pentasodium tripolyphosphate, pentapotassium tripolyphosphate and mixtures thereof. As further defined herein, a phosphate includes the substitution of other phosphates, such as an amount up to 50% of trisodium orthophosphate (Na PO an amount up to of tetrasodium pyrophosphate (Na P O an amount up to 20% of tetrapotassium pyrophosphate (K ,P O and an amount up to 30% of pentasodium tripolyphosphate hexahydrate, for a portion of the pentasodium tripolyphosphate and pentapotassium tripolyphosphate.

With respect to sodium tripolyphosphate, i.e., pentasodium tripolyphosphate, it is suitable to use Form I sodium tripolyphosphate alone, Form II sodium tripolyphosphate alone or a combination of Form 1 and Form II sodium tripolyphosphates. This is one of the advantages of the present invention since it is not critical to have a certain amount of Form I and a certain amount of Form II when sodium tripolyphosphate is employed in a detergent tablet. Form I and Form II sodium tripolyphosphates and their properties are well-known in the art (US. Pat. Nos. 3,056,652 and 2,897,155).

Another essential ingredient in the detergent tablet of the present invention is a detergent. As defined herein, a detergent is a nonionic detergent, an anionic detergent or a mixture thereof. The detergent generally comprises about 4% to about 13% by weight, preferably, 9% to 12%, based upon the total weight of the detergent tablet. If employed, the nonionic detergent may be any of those known in the art including the ones specifically mentioned above for the Black and Gray tablet. In addition, the Pluronic-type detergents disclosed in US. Pat. No. 2,425,845 are applicable.

It is also within the scope of the present invention to use in the tablet an anionic detergent alone or in combination with a nonionic detergent. Any surface-active agent recognized in the art as being an anionic detergent is suitable herein. This includes, among others, the following anionic detergents: alkylaryl sulfonates in which the alkyl portion may be either branched or straight chain, the acyl isothionates, the acyl taurates, alkyl sulfates, the sulfated fatty alcohol ethylene-oxide condensates, alkyl taurines, hydroxy-alkyl taurines and the N (2 alkyl)- sulfoalkanamides.

As stated heretofore, it is critical in the Black and Gray tablet for the weight ratio of the phosphate to nonionic detergent to be within the range of about 2:1 to about 20:1. Another advantage of the present invention is that a suitable product may be formed even if the phosphate to detergent ratio is not within the aforementioned range.

It is also necessary to employ 2% to 11% of water in the preparation of the tablet of the invention. This provides the aforementioned required caustic concentration of at least 23.5%.

The detergent tablets of this invention may have other components optionally include therein. For example, a tablet may have one or more inorganic builder salts, such as sulfates, carbonates and silicates of an alkali metal. About 0.25% to about 75% by weight, preferably 19% to about 30%, of the builder salt may be used in the tablet. If a silicate is employed, however, the amount of silicate may be limited since it may contribute equivalents of Na O. As stated heretofore, the total caustic in the detergent tablet must be between 0.48% and 2.6%. Other optional components include a small amount, e.g., up to about 1%, of fluorescent dyes or optical brighteners; soil-suspending agents; perfumes; water-disprsible colorants; pigments or dyes; and mixtures thereof.

The procedures heretofore described in the Black and Gray process are applicable for the preparation of the instant detergent tablets. The essential components and optional components are blended together until a uniform mixture is obtained. Preferably, the caustic is combined with an aqueous silicate solution and the solution with the caustic is sprayed into a rotating drum with powdered phosphate and detergent therein. The agglomerated mixture therefrom is usually screened. The mixture is then compressed into tablets with any desired shape, such as a cylindrical shape. The compressed tablets may be treated subsequently by moistening the surface of the tablets with 0.1% to 0.4% by weight of water. It is also within the purview of the present invention to chill the compressed tablets, either with or without prior surface moistening, to accelerate the strengthening of the tablets. The chilling may be performed by exposing the tablets to substantially quiescent or moving cold air at a temperature not above about F. for at least 5 minutes.

It is also advantageous in this invention to compress with rotary dies. This will effect compressive forces which rotate around the axis of compression with respect to the tablet. The rotation should be sufficient to provide a shearing force on the faces of the tablet in order to preclude the adherence of the mixture being compressed on the die. The mixture of this invention with the caustic therein has a greater tendency to adhere to the dies when it is being compressed into tablets. The use of rotary dies, therefore, facilitates production since the dies do not have to be cleaned as frequently. The detailed procedure for employing rotary dies to form compressed tablets is described in US. Pat. No. 3,081,267 which is incorporated herein by reference.

Thus, in a first embodiment of the invention a detergent tablet is provided from a detergent, a phosphate, water and a critical amount and concentration of caustic. This tablet is substantially free from undesirable needle-like crystals as evidenced by its relatively high initial (fresh) strength after being compressed and by its ability to dissolve in water in less than about 1% minutes under the usual household washing machine operating conditions. The tablet of the invention has the required plate-like crystals as evidenced by the fact that the mixture, prior to compression to a tablet, is not mushy.

A second embodiment of the invention is the treatment of a phosphate, per se, with caustic. Phosphate and caustic in this embodiment have the same definitions as in the aforementioned first embodiment.

In the second embodiment, it has been found that the formation of undesirable needle-like crystals is prevented by treating the phosphate with at least 4% caustic, such as sodium hydroxide. As defined in the first embodiment, the percentage of caustic is based in part on equivalents of Na O. However, the percentage of caustic is also based in part on the weight of the phosphate. In order to provide the required concentration of 23.5% as NaOH, about 4% to about 26% water, based on the weight 'of the phosphate, is employed with the caustic.

The treatment of the phosphate with caustic may have either one of two desired effects in this second embodiment. Firstly, it may promote or permit the growth of plate-like crystals in the phosphate rather than needle-like crystals. This is accomplished by using at least the minimum amount of caustic, i.e., 4%. Secondly, the phosphate may be treated with an even greater amount of caustic to preclude any crystal formation therein including both the needle-like crystals and also the plate-like crystals.

The treated phosphate of the second embodiment with plate-like crystals has utility as shown above in detergent tablets. The treated phosphate without any crystals therein also has utility since it may be used in other detergent composition-s besides tablets, such as powders and flakes. The present invention has a third embodiment. The third embodiment is concerned with a detergent tablet containing a phosphate and a detergent having plate-like crystals therein without the caustic of the first embodiment. The definitions for phosphate and detergents are the same as in the first embodiment. The proportions of the essential phosphate and detergent components and the optional components are also the same as in the first embodiment. It has been discovered in the third embodiment that a phosphate, which does not have acid decomposition products thereon, may be combined with a detergent, e.g., an anionic detergent and a cationic detergent, to provide a detergent tablet also having high initial strength after compression and having the ability to dissolve quickly in water. Since there are no acid decomposition products, the tablet has desirable plate-like crystals rather than undesirable needle-like crystals.

In the third embodiment, a preferred tablet is one provided from a nonionic detergent and a phosphate. It has been found that this tablet does not dissolve or disintegrate in boiling alcohol, e.g., 300 ml. absolute ethyl alcohol which is allowed to boil for about five minutes. This is surprising since a tablet containing an anionic detergent and phosphate does dissolve and disintegrate in boiling alcohol and since the nonionic detergent, per se, is soluble in alcohol.

The following examples are submitted to illustrate but not to limit this invention. Unless otherwise indicated, all parts and percentages in the specifications and claims are based upon weight.

Example I Detergent tablets were prepared from the formulations indicated in Table I. This was accomplished by incorporating powdered phosphate and sodium sulfate into a revolving drum. A first liquid mixture of Sterox DJ and Pluronic F68 was then sprayed into the drum over an 8-10 minute period. Subsequently, a second liquid mixture of the sodium hydroxide, silicate and water was sprayed into the drum over an 8-10 minute period to agglomerate the particles therein. The agglomerated granules therefrom were screened by passing them through an 810 mesh screen. The screened granules were compressed thereafter in a die of a Stokes Duplex press at a pressure of about 500 psi. to form tablets.

The initial (fresh) strength of the tablets after compression was determined by the fracture strength test described above for the Black and Gray tablets. The fraction strength of the tablets after they were cooled and stored thereafter for 24 hours was also determined. The results of these tests are also indicated in Table I.

TABLE I Formulations 1 5 (wt. percent) Ingredients Sterox DJ 4. 5 4. 5 Pluronic F-68 5. 5.0 Pentasodium tripolyphosphate, Typ 00.0 60. 0 20 Sodium silicate solids (N820 2 4510s) 6. 6. 5 N aQH (100% 0. 3 16. 0 15. 7 8.0 8. 0

100. 0 100. 0 Calculations: NazO equivalent to silicate plus caustic (percent)... 1. 90 2. 13 20 NaOH equivalent to silicate plus caustic (percent) 2. 45 2. 75 H2O in silicate (percent) 7. 45 7. 45 E added as water (percent) 0.55 0.55 Total H added (percent) 8.0 8.0 Total NazO in water (percent) 19. 2 21.0 Total NaOH in. water (percent). 23. 4 25. 6 Results: Strength, fresh (lbs) 2. 75 4. 0

Strength after 24 hrs. (lbs) 17 59 This example demonstrates that a tablet containing a phosphate and a detergent may have a relatively low initial strength after compression. This is due to the presence of undesirable needle-like crystals in the tablets.

By incorporating a critical amount and concentration of caustic into the tablet, however, a product is formed which has a relatively high initial strength after compression. This is due to the presence of desirable platelike crystals therein.

Example II Tablets were prepared in a similar manner as described for Example I with the formulations listed in Table II. The sodium carboxymethylcellulose was added initially to the drum with the powdered phosphate and sulfate.

The initial fracture strength of the compressed tablets and the fracture strength after 24 hours were determined as in Example I. These strengths are also listed in Table II.

TABLE II Formulations Ingredients Sterox DJ 4. 5 4. 5 4. 5 4. 5 4. 5 Pluronic F-Gtl 5.0 5.0 5.0 5.0 5.0 Pentasodium tripolyphosph 60.0 50. 9 59. 8 59. 8 50. 7 Sodium silicate solids A 6. 5 6. 5 6. 5 6. 5 6. 5 Sodium sulfate 14. 8 14. 8 14. 8 14. 7 14. 7 Sodium carboxymethyl cellulose. 0. 56 0. 56 0. 56 0. 56 0. 56 NaOH (added) 0.07 0.14 0.21 0. 28 Water (plus miscellaneous) 8. 64 8. 67 8. 70 8. 73 8. 76

100. 00 100. 00 100.00 100. 00 100. 00 C alculations:

Formulation weight in lbs. 3, 500 3, 504. 9 3, 509. 8 3, 514. 7 3, 519. 6 NazO calculated from silicated added (lbs 66.88 66. 88 66.88 66.88 66. 88 NaOH calculated from silicate added (lbs 86. 30 86.30 86. 30 86.30 86. 30 N320 calculated from caustic soda (lbs) 0 1.90 3.8 5. 70 7. 6 NaOH calculated from caustic soda (lbs 2.45 4. 9 7.35 9.8 H20 added with silicate (lbs. 26.07 26.07 .07 26.07 26.07 H2O added as water (1135).. 3 30 2630 30 30 E20 added with caustic soda 0 2.45 4. 9 7. 35 9.8 Total NazO in water (percent) 18.8 19.0 19. 3 10. 6 19. 9 Total N aOH in water (percent)- 23. 0 23. 3 23. 6 23. 9 24. 2 Total water (lbs) 298. 1 300. 55 303.0 305. 45 307. 9 R 1x120 in silicate+caustic (total formulation basis, percent)" 1. 91 1. 06 2.01 2.06 2. 12

esu 5:

Strength, fresh (lbs) 2. 2 2. 3 2. 7 2. 8 3. 5 22 25 23 23 23 Strength after 24 hrs. (lbs) 1 Type I; 20% Form 1, Form 11 2 Based on the addition of 6.5% Rusilicate solids; Ru silicate is a silicate solution in which 13.7% is N810,

32.9% SiOz and 53.4% water; NazO .2.4S1O2.

3 The 30 lbs. of water in each formulation is considered as extra water to allow for evaporation and is not included in the formulation weight.

' cal amount and concentration of caustic, i.e., between It is manifest from this example that a tablet with a relatively low initial strength after compression may be provided from a phosphate and a detergent indicating undesirable needle-like crystals therein. By using a criti- 0.48% and 2.6% equivalents Na O with a concentration of at least 23.5% as NaOH, a tablet is formed with a relatively high initial strength after compression indicating desirable plate-like crystals in the tablet. If less than Example III shows that using more than the critical amount of caustic will have an adverse effect in providing a detergent tablet. This is due to the fact that too much caustic will preclude the formation of desirable platelike crystals.

Example IV The procedures, described above for Example II, for preparing and testing tablets were repeated with the formulations in Table IV.

TABLE IV Formulations (percent) Ingredients Sterox DJ 4.5 4. 5 4. 5 Pluronic F438 5.0 5.0 5. Pentasodium tripolyphosphate (20% Form I80% Form 11). 60.0 59.8 59. 6 Ru silicate solids of Example 11 6. 6.5 6. 5 Sodium sulfate 8 14. 8 14. 7 Sodium carboxyrnethyl cellulose. 5 0. 5 0. 56 Added Na H .1 0.28 Water (plus miscellaneous) 8.86

100.00 Caleulatronsa Total weight (lbs.) 3, 510 3, 510 3, 520 N320 calculated from silicate added (percent) 1. 91 1. 91 1.91 NaOH calculated from silicate added (percent).. 2. 47 2. 47 2. 47 N820 calculated irom caustic soda (percent)... 0.11 0. 22 NaOH calculated from caustic soda (percent) 0.14 0.28 E 0 added with silicate (percent). 7. 45 7. 45 7. 45 H2O added with water (percent) 0. 86 0. 86 0.85 H added with caustic (percent). 0.14 0.28 Total NazO in water (percent) 18. 7 19. 3 19. 9 Total NaOH in water (percent) 22. 9 23. 6 24. 2 Nero in silicate+eaustic (total formulation basis,

percent) 1.91 2 02 2 13 Results:

Strength, fresh (lbs.) 3.4 4. 6 5.4 Strength after 24 hrs. (lbs.) 24.4 27. 5 29. 4

the critical amount and concentration of caustic is used, however, the initial strength of the compressed tablet is still relatively low since the tablet has the undesirable needle-like crystals rather than the desirable plate-like crystals therein.

Example III TABLE III Formulation Ingredients: (pounds) Pentasodium tripolyphosphate, Type I 2100.000 Sodium sulfate 518.000 Sodium carboxymethylcellulose 26.100 Sterox DJ 157.200 Pluronic F-68 174.600 Fluorescent dye 7.000 Sodium silicate solution at 46.6% solids (Na O-2.4SiO 487.000 Colorant 0.042 Perfume 3.950 NaOH (50%) 88.500

Total 3562.392

Calculations: 35 Na O calculated from silicate (lbs.) 66.7 Na O calculated from caustic (lbs.) 34.3 Water added with silicate (lbs.) 260 .1 Water added with caustic (lbs.) 44.3 NaOH calculated from silicate and caustic 70 (lbs.) 130.3 Na O in water (percent) 24.9 NaOH in water (percent) 30.0 Na O in silicate-l-caustic (total formulation basis, percent) 2.8

It is evident from the above data that a tablet with a relatively low initial strength after compression may be formed because there are undesirable needle-like crystals therein. However, a tablet with a relatively high initial strength after compression is formed by using a critical amount and concentration of caustic to prevent the formation of undesirable needle-like crystals but to permit or promote the formation of desirable plate-like crystals.

The tablets from formulations 2 and 3 in Example IV were also tested to determine their rate of disintegration and solubilization. The tablets, 40 at a time, were placed in a washing machine and agitated with water at 100 F. for seconds. Almost all of the tablets had completely disintegrated and dissolved after this time period.

Besides having a relatively high initial strength, a detergent tablet of this invention, as shown in Example IV, disintegrates rapidly in water.

Having set forth the general nature and specific embodiments of the present invention, the true scope is now particularly pointed out in the appended claims.

What is claimed is:

1. A detergent tablet having a high initial strength after compression and having the ability to disintegrate and dissolve rapidly in water which consists essentially of about 4% to about 13% of a synthetic organic nonionic detergent, about 5% to about of a phosphate which is selected from the group consisting of pentasodium tripolyphosphate, pentapotassium tripolyphosphate and mixtures thereof, 0.48% to 2.6% caustic which is a source of Na O or K 0, which is capable of forming a solution in water with a concentration based on equivalents of Na O of at least 23.5% as NaOH and which is selected from the group consisting of sodium hydroxide, potassium hydroxide, alkali metal silicates and mixtures thereof, and 2% to 11% water in order that there is a concentration of at least said 23.5 caustic in water.

2. A process for preparing detergent tablets having high initial strength after compression and having the ability to disintegrate and dissolve rapidly in water which comprises mixing together about 4% to about 13% of a synthetic organic nonionic detergent, about 5% to about 95 of a phosphate which is selected from the group consisting of pentasodium tripolyphosphate, pentapotassium tripolyphosphate and mixtures thereof, 0.48% to 2.6% caustic which is a source of Na O or K 0, which is capable of forming a solution in water with a concentration based on equivalents of Na O of at least 23.5% as NaOH and which is selected from the group consisting of sodium hydroxide, potassium hydroxide, alkali metal silicates and mixtures thereof, and 2% to 11% water in order that there is a concentration of at least said 23.5% caustic in water; and compressin the mixture at a pressure necessary to form tablets.

3. A process for preparing detergent tablets having high initial strength after compression and having the ability to disintegrate and dissolve rapidly in water which comprises mixing together about 4% to about 13% of a synthetic organic nonionic detergent, about 20% to about 95% of pentasodium tripolyphosphate, 0.48% to 2.6% caustic which is a source of Na O or K 0, which is capable of forming a solution in water with a concentration based on equivalents of Na O of at least 23.5% as NaOH and which is selected from the group consisting of sodium hydroxide, potassium hydroxide, alkali metal silicates and mixtures thereof, and 2% to 11% water in order that there is a concentration of at least said 23.5% caustic in water until granules are formed; passing the granules through an 53-10 mesh screen; and compressing the screened granules into tablets at a pressure of about 200 to 5000 pounds per square inch using compressive forces rotating around the axis of compression with respect to the tablet being formed to effect a shearing force on the basis of said tablet thereby preventing the tablet from adhering to the pressing means.

4. A detergent tablet having a high initial strength after compression and havin the ability to disintegrate and dissolve rapidly in water which comprises 4.5% of the condensation product of 1 mole of dodecyl phenol with an average of 10 moles of ethylene oxide, 5.0% of HO 2 4 a s s b (CZHIIO c in which (C H O) represents a molcular weight of 1501- 1800 and n+ is an integer such that the molecule contains 8090% ethylene oxide, 60% of pentasodium tripolyphosphate with 20% as Form I and 80% as Form II, 6.5% of Na O-2.5SiO 0.3% of NaOH, 15.7% of sodium sulfate and 8.0% water; said tablet having Na o equivalents of 1.9% and having 25.6% concentration of total NaOH in water.

5. A detergent tablet having a high initial strength after compression and having the ability to disintegrate and dissolve rapidly in water whichcomprises 4.5% of the condensation product of 1 mole of dodecyl phenol with an average of moles of ethylene oxide, 5.0% of HO(C H O) (C H O) (C H O) I-I in (C3H 0) represents a molecular weight of 1501-1800 and a+c is an integer such that the molecule contains -90% ethylene oxide, 59.7% of pentasodium tripolyphosphate with 20% as Form I and 80% as Form II, 6.5% of Na O-2.5- SiO 0.28% of NaOH, 14.7% of sodium sulfate, 0.56% of sodium carboxymethylcellulose and 8.76% of water; said tablet having Na O equivalents of 2.12% and having a 24.2% concentration of total NaOH in water.

6. A detergent tablet having a high initial strength after compression and having the ability to disintegrate and dissolve rapidly in water which comprises 45% of the condensation product of 1 mole of dodecyl phenol with an average of 10 moles of ethylene oxide, 5.0% of HO(C H4O) ,(c3H5O) (C2H4O) H in (C3H 0)b represents a molecular weight of 150l1800 and a+c is an integer such that the molecule contains 8090% ethylene oxide, 59.6% of pentasodium tripoylphosphate with 20% as Form I and 80% as Form II, 6.5% of Na O-2.5- SiO 0.28% of NaOH, 14.7% of sodium sulfate, 0.56% of sodium carboxymethylcellulose and 8.86% water; said tablet having Na O equivalents of 2.13% and having a 24.2% concentration of total NaOH in water.

7. The detergent tablet according to claim 1 in which the caustic is NaOH.

8. The detergent tablet according to claim 1 in whic the caustic is a mixture of NaOH and Na O-2.4SiO

9. The process according to claim 2 in which the caustic is NaOH.

10. The process according to claim 2 in which the caustic is a mixture of NaOH and Na O-ZASiO 11. The detergent tablet according to claim 1 in which the phosphate is substituted with an amount up to 50% of trisodium orthophosphate, an amount up to 20% of tetrasodium pyrophosphate, an amount up to 20% of tetrapotassium pyrophosphate or an amount up to 30% of pentasodium tripoly-phosphate hexahydrate.

References Cited UNITED STATES PATENTS 2,811,419 10/1957 Hartlapp et al. 252- 2,909,490 10/1959 Metziger 252135 2,961,410 11/1960 Martin 252--135 2,987,483 6/1961 Brooker 252135 3,081,267 3/1963 Laskcy 252l35 3,174,934 3/1965 Shen 252135 FOREIGN PATENTS 1,050,005 2/1959 Germany.

LEON D. ROSDOL, Primary Examiner.

B. BETTIS, Assistant Examiner.

US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,417 ,024 December 17 196 Seymore Goldwasser It is hereby certified that error appears in the above numbered pat ent requiring correction and that the said Letters Patent should read as corrected below.

Column 2 lines 8 and 10 "[C H OJ each occurrence Should read s fi b Column 4, TAIsLE A, under the heading "18", line 15 thereof, cancel "l8" and insert the same under the heading "19" line 15. Column 6, line 47,

after "The" insert difference between plate-like crystals and the needle-like Column 8, line 30, "The" should read This Columns 9 and 10, TABLE II, under the heading "3" line 15 thereof, ".07" should read 26 .07 same TABLE II, under the same heading "3", line 16 thereof, "2630" should read 30 Columns 11 and 12, TABLE IV, under the heading "1" line 10 thereof, "3,510" should read 3,500

Signed and sealed this 2nd day of September 1969.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM SCHUYLER, Attesting Offic r Commissioner of Patents 

